THE SEPARATION OF THE CRYSTALS 427 



The Continuous Centrifugal. — A number of inventors have attempted to 

 develop machines which will operate continuously and avoid the time and 

 power lost in starting and stopping and in charging and discharging. No 

 great success has been obtained so far, but the principles applied are : — 



1. A horizontal machine, in which rotates a screw moving at a slightly- 

 lower speed than the basket, whereby the material is propelled forward and 

 discharged dry at the end of the machine remote from the inlet. This idea 

 is contained in Aspinall's patent (1196, 1855), and has been in particular 

 developed by Stewart (6931, 1884, and 13655, 1888). 



2. A fluid introduced into a rapidly rotating vertical cylinder will tend 

 to rise against gravity, precisely as is observed in the ordinary machine. 

 This tendency may be assisted by maintaining communication with the 

 incoming material by defining a passage for its motion. In such a scheme 

 it is intended that the dried material should eventually discharge itself 

 over the lip of the basket. This device is included in Bessemer's patent 

 (13202, 1850), in Aspinall's (2833 of 1855), and in several later ones. 



3. If the shell of the ordinary machine be removed or opened when the 

 basket is at speed the wall of dried sugar will be expelled. This idea is 

 developed in patents 13846, 185 1, and 1433 of 1854, ^^^ by Abel, 22900 of 

 1905. 



4. Another patent, also due to Abel (14736 of 1889) places a number of 

 baskets inside the main basket and located around its periphery. These 

 baskets rotate with the machine and simultaneously about their own axes. 

 They are divided into compartments by radial partitions, and located about 

 the centre of each basket is a cone. Massecuite is fed into the cone and 

 thrown into those compartments furthest from the axis of the main basket^ 

 whence the molasses is expelled by the usual action. As the baskets rotate 

 about their axes each compartment in turn will arrive at a position when the 

 wall of the basket lies between the sugar contained therein and the axis of 

 rotation of the main basket. In this position the sugar is thrown out against 

 the outer side of the cone and falls into a funnel-shaped receptacle, which 

 directs it to the conve^^or. 



REFERENCE IN CHAPTER XX. 

 I. C. R., 1847, 24 1074. 



